The present invention relates to a tying device made of synthetic resin which is used to tie a plurality of electric wires or similar linear objects, or to close the opening of a bag. More particularly, it provides a tying device which is formed as a band of a thick plate configuration and which may appropriately be loaded in a tying machine wherein the tying device is bent from a thin portion formed at a central part thereof whereby a claw-like first engaging portion comes into engagement with an annular second engaging portion.
There has hitherto been known a tying device made wholly of synthetic resin such as nylon, polypropylene and the like in which it is formed as a band including thick portions and is bent from a thin portion formed at a central part thereof, in which a first engaging portion in the form of a claw or projection is provided at the end of one of the thick portions while an annular second engaging portion is provided at the end of the other thick portion extended from the above-mentioned thick portion via the thin portion, and in which linear objects such as electric wires, filaments, bags or the like are held between the two thick portions and are tied together by inserting the claw-like first engaging portion into the annular second engaging portion.
In such tying device, a considerable amount of biasing force is necessary to engage the first engaging portion with a hole of the second engaging portion. In addition, the tying device per se is of relatively small size. Hence, a tying operation is difficult to perform by hand and a tying machine is thus employed.
The tying machine is provided along the longitudinal axis with a guide slot in which the tying device is fitted. While the objects such as electric wires and the like are placed on the tying device, the tying device is bent from the thin portion so as to hold objects between the two thick portions. In this state, the claw of the first engaging portion is fitted into the engaging hole of the second engaging portion thereby to tie the objects.
In use and operation of the tying machine, it is necessary to push the tying device forward to the front end of the guide slot and to bend the thick portions to a V-configuration by means of rocking action of a rocking arm of bending member which may be moved and rocked forward and backward by a lever thereby to fit the claw of the first engaging portion into the hole of the second engaging portion.
However, in the case of the prior art tying devices, the thick portion pressed upward by means of the rocking arm is often released from the rocking arm in the course of bending the tying device by pressing the under side of one thick portion in the tying device by means of the rocking arm or bending member. In this case, the tying device must be removed from the tying machine once and again fitted therein so as to operate the tying machine. Accordingly, the tying operation may not smoothly be performed. The release of the tying device from the rocking arm tends to increasingly occur as the operational velocity of the tying machine increases.
In the above-mentioned tying machine, a piece of tying device is fitted in the guide slot provided along the longitudinal axis of the tying machine and is moved forward. While the thick portion having the second engaging portion is shifted to the front part of the tying machine in a fixed state, linear objects such as electric wires and the like are placed thereon. Then, the thick portion having the first engaging portion is pressed upward by means of the rocking arm and is further bent against the electric wires or the like while fitting the claw-like first engaging portion formed at the rear thick portion into the annular second engaging portion of the thick portion positioned under the electric wires or the like.
Problems to be faced in this tying machine are such that a considerable amount of force is required to bend the tying device along the longitudinal axis thereof and the tying operation must instantaneously be performed. In the prior art tying device, however, the under side of the thick portion is in the form of a plane and the rocking arm or bending member is in the form of a plate. In this construction, when the under side of the thick portion in the tying device is pressed by the end surface (in the thickness direction of a plate) of the rocking arm, the under side of the thick portion to be bent is liable to slip from the rocking arm. As a result, the tying operation may not properly be performed or is totally impossible.